1. Field of the Invention
The present invention relates to a drive assist device for a vehicle for carrying out automatic steering control by generating steering wheel torque that follows a preceding vehicle.
2. Description of Related Art
In recent years, there has been research and practical implementation of follow-up traveling control follows the preceding vehicle and traveling control device keeps a distance between the vehicle and the preceding vehicle constant, by detecting traveling environment in front of the vehicle using cameras mounted on the vehicle and detecting the preceding vehicle from the traveling environment data.
For example, Japanese Patent Laid-open No. 2003-81123 discloses technology, in a steering control system for a vehicle that detects a traveling lane to cause a vehicle to follow along the traveling lane, for calculating a target yaw rate using forward viewpoint lateral displacement, vehicle speed, and forward viewpoint distance, and generating steering wheel torque so as to obtain the calculated target yaw rate.
However, with the steering control system as disclosed in Japanese Patent Laid-open No. 2003-81123 described above, since target yaw rate is set to carry out steering control, in a specified control region, particularly in a region where sufficient yaw rate is not being generated, such as a low speed region, it is not possible to accurately set a travel locus to be made a target, and there is a problem that it is not possible to carry out follow-up control with respect to the preceding vehicle with good precision.
The present invention has been conceived in view of the above-described problems, and an object of the present invention is to provide a vehicle drive assist device that can accurately obtain a travel locus to be followed even in, for example, a low speed travel region, and that can carry out follow-up control with good precision.